Phonograph sound box



B. FRITZSCH.

PHONOGRAPH SOUND BOX.

APPLICATION FILED JAN. 25. 1921.

1,437,799. Patented Dec. 5, 1922.

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Grammy Patented Dec. 5, 1922.

UNITED STATES BERNHARD FRITZSCH,

or CINCINNATI, OHIO.

PEONOGRAPH SOUND BOX.

Application filed January 25, 1921.

T 0 all whom it may concern:

Be it known that I, 'BnRNHAnn FRirzscH, a citizen .of the United States, and residing at Cincinnati, in the county of Hamilton and State-of Ohio, have invented a new and useful Improvement in Phonograph Sound Boxes, of which the following specification is a full disclosure.

My invention relates to an improved sound-box for phonographs and the present invention is specifically an improvement over the sound-box disclosed in my prior Patent No. 1,217,294, Feb. 27, 1917.

More particularly the invention relates to the construction and material of the diaphragm. My said prior diaphragm possessed a very superior tone quallty, but being of wood it was subject to warping, contraction and expansion, and to non-uniform elasticity. It was relatively flexible atone diameter and relatively less flexible at the transverse diameter, due to the grain of the wood.

The object of my present invention to retain the desirable tone characteristics of a wood diaphragm but without the objections stated. I therefore produce a diaphragmhaving a wood-like composition, but of uniform resilience. For this purpose, I preferably use a composition of matter comprising largely wood pulp, leather scraps. a small amount of rubber, and some binder as casein or lime. The material is finely ground, mixed andpressed in a. wet state into about onesixteenth inch board thickness. This is hard, when dry, and wood-like, but not grained, and is uniformly flexible.

It is more desirable, constant and dependable than wood.

The composition board cut into disksand ground down to about a one-thirty-second inch thickness ,of uniform cross-section.

In the drawings:

1 shows a face view of my diaphragm.

Fig. 2 a cross section of the same.

3 an element of my complete soundbox. 4

Fig. 4 is a central vertical section of the same.

The sound-box proper is conventional, having the tone arm 1, and the usual diaphragm holder 2, and needle arm 3.

Preferably, the central portion of the wood composition disk 4 is formed with a central orifice and this opening is covered by a central disk 5 which is relatively less Serial No. 439,869.

. resilient, and this minor disk is preferably made of wood, and of greater cross section than the composition portion 4 of the diaphragm. It is adheslvely secured thereto and the needle arm is attached to the center of this small disk. Preferably, this disk 5 is placed on the outer surface of the diaphragm, and the relative areas of the disk are indicated by the scale drawing indicating dimensions producing the best results.

I have found that the tone is very superior to the all wood or natural wood diaphragm, and that it has superior property of recording or reproducing all overtones with distinctness and naturalness. This is particularly noticeable in piano and violintones, in

which the overtones are the most elusive. Comparison of this diaphragm with the one of my former patent, shows marked improvement, for instance, in the piano bass notes, or in the violin harmonic tones, which is a recording and reproducing test of the most rigid character.

This diaphragm when dried, hard, and varnished is secured in the holder in the usual manner.

Having tried a wide range of materials adaptable. l have found. best results i the diaphragm composed and constructed a closed. This diaphragm is about as toneneutral as it is possible to constitute, and hence does not by its own vibration, color the tones to be recorded or reproduced.

I do not desire to be limited to the exact composition or to the exact ingredients or proportions. IIeither do I desire to be limited to the specific structure, since in the light of this disclosure, the principles inhering in this discovery may be understood and reduced to practice with some considerable latitude.

Having described my invention, I claim:

A diaphragm for the sound box of a phonograph consisting ofa composition matter comprising wood pulp, leather, a small amount of rubber and binding agents, formed into a hard, non-grained and uniformly resilient disk, adapted to be secured in asound ing box.

In witness whereof, I hereunto subscribe my name, as attested by the two subscribing witnesses.

BER-NHARD FRITZSCH. Witnesses:

L. A. BECK, J. C. JUNIUB. 

